0023-6152

AA00697606

22793

Unrefereed

0023-6152

AA00697606

Effective integrated rat control procedures are of pressing importance to the Pacific islands not only because of extremely heavy rat damage to coconuts but also the consequent transformation of coconuts into larval habitats for mosquitoes, including vectors of Bancroftian filariasis and dengue. Such procedures call for the joint use, against an adequate background of ecological knowledge, of chemical and biological control measures. In controlling rats on large numbers of small, scattered islands, such as those of the Pacific including the Ryukyus, biological control involving the use of predators might be especially important from the ecological and economic points of view. In this connexion, the potentialities of the Japanese weasel, Mustela sibica itatsi Temminck & Schlegel, as a rat control agent, were advanced in an earlier contribution (Uchida, 1966). At the same time, attention was directed to the great importance of this field trial in the Ryukyus as a preliminary test to further experimental introduction elsewhere in the tropics. To appraise whether this weasel merits consideration for field trial in Micronesia or Polynesia for the purpose of evaluating its effectiveness as a rat control agent in coconut plantations, the present study was thus undertaken on several islands of the Ryukyus, into which the predators had been introduced. In consequence, it is concluded that further consideration of the possibiIity of experimental introduction of the weasel into the South Pacific is warranted. M. sibirica itatsi is thus discussed in further detail with special reference to its environmental requirements, the feasibility of establishing it under tropical conditions and its combined use with anticoagulant rodenticidcs. It must nevertheless be emphasized that reasons of nature conservation should preclude any introductions into certain islands set aside as sanctuaries for indigenous animals (especially sea birds), or otherwise of special importance as breeding grounds for such fauna.